Furnace grate



April 21, 1925.

F. H. M"FIUGH FURNACE GRATE Filed March 18, 1921 3 Sheets-Sheet 1 M H. mw

F. H. M HuGH FURNACE GRATE r il 21 Sheets-Sheet 2 Filed March 18. 1921 FIG--4- oooo0ooooo LODooOoOoou N I 1 H I ATTORNEY A ril 21, 1925.

INVENTOR ATTORNEY Patented Apr. 21, 1925.

PATENT OFFICE.

UNITED STATES FRANK H. MOHUGH, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TO CHARLES A. MGHUGH, OF PHILADELPHIA, PENNSYLVANIA.

FURNACE GRAIIE.

Application filed March 18, 1921. Serial No. 453,293.

To all whom it may concern:

Be it known that I, FRANK H. MGHUGH, a citizen of the United States, and resident of Philadelphia, county of Philadelphia, State of Pennsylvania, have invented an Improvement in Furnace Grates, of which the following is a specification.

My invention has particular reference to travelling grates, such as employed in automatic stokers, and has for its object the pro- .vision at each side of the grate, (adjacent to the brick lining of the furnace chamber), of upwardly extending hollow air supplying metallic or other walls approximately as high as the normal maximum fuel bed to be carried by the grate, whereby the fuel upon the grate will not be required to travel in direct contact with the the brick or other lining, thereby preventing rapid wear and adhering clinkers, clauses heretofore of frequent shut downs and repairs.

My object is further to provide the said upwardly extending side walls in such manner as to form part of the detachable and replaceable elements of the travelling grate and whose function is to prevent incandescent fuel travelling in contact with the overheated brick lining and clinker formations on the side walls. Heretofore the pro duction of such clinker-s has caused the breaking up of the fire bed adjacent to the walls, permitting objectionable free upward passage of air through the lire bed with the result of chilling of the furnace gases and providing such an excess pressure within the furnace that hot coal and cinder are blown out through any side openings between the grate and the lining, thereby clogging the grate supporting and operating means and frequently burning the frame or other part in an objectionable manner. These objec tions are overcome by my improvements.

My invention is applicable to various types of travelling grates, including those in which the bars connected by chains are provided with replaceable keys or grate bar' sections, those in which the grate is formed of links arranged side by side and hingedly connected to form a travelling web, or in which the grate constitutes a large number of plate sections travelling in unison under the propelling power of chains, all of which are well known forms of travelling grates.

My invention being applicable to all forms of travelling grates, I do not restrict myself to any special design of that portion of such structures which directly carry the fire bed while permitting the upward passage of air, as my object is to provide all of these various types of travelling grates with hollow air supplying side portions which extend up- .wardly in alinement when carrying the fire bed to form a shallow trough-like grate surface in which the fire bed is conveyed along relative to the brick lining of the furnace walls without objectionable contact therewith.

lVith the above and other objects in view, the nature of which will be more fully under stood from the description hereinafter, the invention consists in the novel construction of furnace grates, as hereinafter more fully described and defined in the claims.

Referring to the drawings: Fig. 1 is a longitudinal sectional view showing the general typical form of travelling grate of a self-feeding stoker and embodying my in vention there-in; Fig. 2 is a transverse section thereof on line 22 of Fig. 1; Fig. 3 is a side elevation of one of the grate sections, showing my improved side wall applied thereto; Fi l is a cross sectional view of the same, taken on line l-lof Fig. 3; Fig. 5 is a transverse sectional view of a portion of a the grate made up of chain link sections and having my invention applied thereto; Fig. 5 is a longitudinal sectional view of a portion of the same; Fig. 6 is a transverse sectional view of a portion of a furnace and grate embodying my invention in which the grate is made up of keys having a clove tailed connection upon travelling transverse supporting bars connected together by chains; Fig. 7 is a longitudinal sectional view of the grate shown in Fig. 6, taken on line 77 thereof, and illustrating the end where the grate travels about the sprocket wheels; and Figs. 8, 9, and 10, inclusive, are vertical sectional views of portions of the fire grate structure and brick furnace lining adjacent to one side of the fire bed and embodying modified features of my invention.

The drawings are intended to diagramn'iatically illustrate the general characteristics of an. endless grate stoker and are to be taken more by way of illustration rather than restriction, as my invention is applicable to any of the ordinary endless grate constructions now or heretofore in use.

In the particular constructionshown in Figs. 1, f2, 3 and 4-, 2 is the combustion chamber, 9 is the endless grate formed like an endless apron and guided about sprocket wheels 1, 4'. at each end of the grate structure and carried upon transverse shafts/5, 5. In practice, the shaft 5 arranged at the front of the furnace is slowly rotated by suitable power devices (not shown) with the object of causing the upper portion of the grate to travel slowly backward in the direction of the arrow (Fig. 1). The coal is fed from a hopper 6 downward upon the travelling grate and undergoes combustion during its rearward travel and the ash formed thereby is dumped at the rear end 7 of the grate and caused to pass downward through the aperture 8. In the particular illustrationshown, 3 are endless chains arranged to travel about the sprocket wheels 1, so that they all travel at the same rate of speed. Secured to the links of these chains are sectional grate portions 10 having downwardly extending parts 11 which are bolted to the chain links at 12. A series of these grate portions 10 are arranged side by side to constitute a transverse grate section of the full width of the travelling grate, as will be understood by reference to Fig. .2. These grate portions 10 are each provided with vertical slots or air passages 16 for supplying air to the bed of fuel resting upon them. The extreme lateral grate portions 10 are each provided with hollow projecting parts 13 arranged in a plane. perpendicular to the surface of the grate sections and having its hollow interior Hprovided with openings 15 through the wall thereof to permit passage of air for maintaining adjacent parts cool and at thesame time for supplying air to the fuel, the said specially constructed end grate portions, together with all intermediate portions, constituting a transverse grate section which, with other similar sections secured side by side, form the endless apron. Moreover, the plurality of transverse grate sections having their end projecting portions provide, when travelling horizontally, a shallow trough-like grate structure for receiving and conveying the fuel, and whereby it is conveyed through the furnacechamber without direct contact with the brick of the side walls thereof. As the sections 10 and 10 in the same transverse 'alinement are associated and consections.

nected through the chains and sprocket wheels and shafts to move as a unit and always maintain the same relat1ve positions,

they may be considered as a transverse section of the grate and a series of these sections as forming the trough-like structure essential to my invention.

Fig. 5 illustrates a cross section and Fi 5 is a longitudinal section througha portion of a modified form ofthe endless grate, being of that construction which is made up of-a plurality of transversely arranged sets of links 10 and 10 in overlapping ar rangement and jointedly connected by transverse hinge rods 17, which also support side sections 13, preferably made hollow with transverse openings through "the inner walls corresponding to the structure shown in Fig. 4 heretofore described. As in the previous case, these side sections 13" constitute side walls to the grate sections and give the trough-like structure for receiving the fuel. In this particular construction, thebars 1O will maintain transverse alinement and swing together, and with the rod 17 will constitute a structure which may be considered as a transverse section of the grate, the side wall parts 13 being secured in position thereon by the ends of the said rods. A plurality of the sections each made up of the parts 10*, 13 and two rods 17 are connected in series bylink portions 10 (arranged alternately withfthe bars 10") and connecting adjacent rods 17 of adjacent sections, so that the grate is in :general very much like an endless chain formed of links. 'The rods 17 may be' in the form of-bolts. The gen eral construction of a chain grate of this character is well known in commercial use and will need no further description.

Referring to the construction shown in Figs. 6 and 7, 10 represents a transverse grate bar of ordinary construction which is provided with a dove-tail part 18 upon which the usual keys 19 are fitted, said keys constituting the grate surface proper and with the grate bar form one of the grate These keys are notched; at their sides to provide air passages from below the grate bar tothe fuel above. Grate bars 10, each carrying on its upper dove-tail portion a plurality ofthe keys 19 to constitute the grate surface and the transverse grate section of'this invention,areconnected side by side in the direction of their travel to form an endless grate, the several transverse grate bars or sections, being connected to an endless chain 9 at each sideiof the furnace, one of which endless chains is shown in Fig. 6. In this manner, the endless grate is caused to travel in a manner similar to that indicated in Fig. 1. Bolted to the end portions of these transverse grate bar sections 1 c are the upwardly project- HHI ing portions 13 which, as in the previous cases, are made hollow and provided with the lateral passages for keeping them cool and for supplying air to the fuel bed. In general construction, these transverse grate sections will have at each end the upward side portion 13 and when a series of these transverse grate sections are arranged in consecutive order, as shown in Fig. 7, there will be an endless grate of connected grate sections forming a trough-like structure where the grate travels rearwardly with its bed of fuel. As shown in Fig. 6, the side portions 18 fit upwardly into recessed portions 20 in the side walls 2 of the furnace. To prevent loss of air pressure, the space between the grate bar sections and the brick lining may be sealed by the longitudinal stationary plates 21 which rest adjacent to one side upon the tubular metal support 22 through which water or air may be supplied and adjacent to the other side upon the lateral projecting portions of the grate bars, thereby bridging over the gap 23 which otherwise would be formed and through which the air might pass.

Referring to Fig. 8, the modified construction here shown embodies a grate bar structure with the keys fitted to the dovetailed portions similar to that shown in Fig. 6, but in this case the upwardly projecting side portions are made integral with the grate bar frame, as indicated at 13 and provided with lateral air passages 15. Furthermore, in place of ":he sealing plate 21 of Fig. 6, a sealing plate 21, resting upon the upper edges of the travelling side portions 13 may be employed. Otherwise, the general construction and mode of operation is similar to that explained in respect to Figs. 6 and 7.

Referring to the modification shown in Fig. 9, the construction is in all material respects the same as that of Fig. 8, except as to the sealing means. In respect to the sealing means, a long tube 21 rests upon an inclined strip 21, so that the said tube will roll toward the outer surfaces of the side portions 13, and in that manner prevent a passage of air between the said sealing tube and the side portions of the grate bar sections.

Referring to the modification shown in Fig. 10, the construction of Fig. 9 is followed with the omission of the sealing means and with the metal of the side portion reduced, as indicated at 13, and an angle plate 13 of metal or refractory material bolted in position by means of the bolt 22, said angle plate provided with lateral apertures for passage of air to the fuel bed.

From the foregoing description, it will be understood that the endless grate of trough-like form is composed of a plurality of sections jointedly connected in the direction of their travel, so that they are flexible to suit the requirements of an endless grate stoker, and the several transverse grate sec; tions are structures of any suitable character which extend transversely of the width of the apron-like grate and terminate at each end in the side walls arranged perpendicular to the grate surface; said arrangement being irrespective of the particular construction of these grate sections per se, as any ordinary or special character of these grate sections associated into an apron-like structure may be employed, so long as the side walls are associated therewith to provide the trough-like structure for the fuel bed.

It will now be apparent that I have devised a novel and useful construction which embodies the features of advantage enumerated as desirable, and while I have in the present instance shown and described the preferred embodiment thereof which has been found in practice to give satisfactory and reliable results, it is to be understood that I do not restrict myself to the details, as the same are susceptible of modification in various particulars without departing from the spirit or scope of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is

1. In an invention of the character stated, the combination of a combustion chamber, with an endless travelling grate having an air space between the upper and lower layers thereof, said grate consisting of a plurality of independent transverse grate sections jointedly connected to form an endless apron providing a shallow trough-like structure upon its upper travelling surface and having air passages therethrough, said sections having their end portions provided with side walls of uniform height, said walls being hollow and having air pass-ages therethrough on the side adjacent to the fire bed and directly communicating with said air space.

2. The invention according to claim 1, wherein further the hollow side walls are detachably connected to the grate sections by means on the outside of said walls and out of contact with the fuel bed.

3. In an invention of the character stated, an endless grate consisting of a plurality of elements connected in the direction of their travel and each of which is made up of transversely arranged parts associated to simultaneously move in unison to provide a trough-like fuel carrying means the sides there-of formed with hollow side walls pro: vided with air passages therethrough on their sides adjacent to the fire bed and co1n= municating with the air space below the fuel supporting portion of the grate, combined with: lqngiigu gli nal seals held 7 against .lnovgment in the dil ection .of their length, and. bl iqk lining for. the walls of the {30mbu stion chamb'er of the fpn l m ce extgnding aboye the sides of the tpaveli ng, grate, and I said longitudinal} seals le'spgqtifiely arranged between thebrick lifiing and travelinggrate and in yielding contact with the u per and .out eli pa rtp f the libllow side: will s of the unto set my, liguid.

FRANK MCHUGH. 

